Thioarsenates in sulfidic waters.

It has long been recognized that the formation of soluble arsenic sulfur complexes plays a key role for the mobility and toxicity of arsenic in sulfate-reducing environments. Knowledge of the exact arsenic species is essential to understand the behavior of arsenic in sulfidic aquifers and to develop remediation strategies. In the past, monomeric and trimeric thioarsenites were assumed to be the existing species in sulfidic systems. In this study, thioarsenates were identified by IC-ICP/MS in arsenite- and sulfide-containing solutions as well as in a reduced groundwater from a contaminated site. The unexpected finding of an oxidation of As(lll) to As(V) in thioarsenates in strongly reducing systems can be explained by the high affinity between As(Ill) and sulfur. In sulfide-containing solutions without oxidant, As(lll) therefore undergoes disproportionation to thioarsenates (As(V)) and elemental arsenic. It has previously been supposed that mobility as well as toxicity of arsenic increases if the redox state decreases. For sulfidic waters, the opposite is probably the case. Thus, the formation of thioarsenates could be used in connection with remediation strategies. Thioarsenates are highly sensitive to oxygen and pH. This is important for analytical procedures. A loss of soluble arsenic as well as a conversion to arsenite and arsenate may occur if water samples containing thioarsenates are analyzed with conventional methods.

Polymorphisms in the interleukin-4 receptor alpha chain: association with traits of allergy and asthma in an admixed population in Hawaii.

Single nucleotide polymorphisms (SNPs) in the gene encoding the interleukin-4 receptor alpha chain (IL-4R alpha) have been associated with IgE levels or clinical atopy in some populations. Two SNPs that encode S503P and Q576R in the intracytoplasmic domain of the receptor are associated with loss or gain of function, respectively. We investigated the frequency of these SNPs and their association with traits of allergic asthma in 36 unrelated subjects selected from a racially admixed, clinically ascertained study population with family histories of asthma. The frequency of the 1682 T to C substitution that encodes S503P was 0.11 (70 alleles analyzed, from 29 TT homozygotes and 6 TC heterozygotes). The frequency of the 1902 A to G substitution that encodes Q576R was 0.26 (68 alleles analyzed, from 20 AA homozygotes, 10 AG heterozygotes and 4 GG homozygotes). In this atopic admixed sample, no significant association was detected between the variant genotypes and serum IgE levels, percentage of eosinophils, skin test reactivity, diagnosis of asthma or methacholine reactivity. More conclusive findings await clinical characterization of non-atopic, non-asthmatic subjects as well as more efficient and extensive haplotyping.